Power supply

Abstract

To provide a power supply device capable of suppressing a control arithmetic quantity.SOLUTION: A power supply device comprises: a first bridge circuit; a second bridge circuit; a first transformer having a primary winding electrically connected to a third terminal and a fourth terminal of the first bridge circuit; a second transformer having a primary winding electrically connected to a third terminal and a fourth terminal of the second bridge circuit and a secondary winding having one end electrically connected to one end of a secondary winding of the first transformer; a coil having one end electrically connected to the other end of the secondary winding of the first transformer; a third bridge circuit having a first terminal electrically connected to the other end of the coil, a second terminal electrically connected to the other end of the secondary winding of the second transformer, and a third and fourth terminals from which second DC voltage is output; and a controller for controlling phases of the first bridge circuit, the second bridge circuit, and the third bridge circuit on the basis of first DC voltage and the second DC voltage.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a power supply device. [Background technology]

[0002] Patent Document 1 describes a DC-DC converter using the DAB (Dual Active Bridge) method. DAB allows for isolation, and easily enables step-up / step-down operation and bidirectional power conversion. However, DAB has a characteristic that the current circulating in the circuit increases when the voltage difference between the input side and the output side is large. This characteristic does not decrease even if the phase difference between the input side and the output side, which is the command value of the output current, is set to 0 degrees. Therefore, under conditions where a significant input / output voltage difference occurs, such as output side droop (short circuit), a current increase occurs in almost all elements through which current flows, which is greater than that in the normal operating range. This causes a problem of significant increases in circuit stress and loss.

[0003] Patent Document 2 describes a switching power supply device that solves the above problem by controlling the phase of each transistor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Pat. No. 5,027,264 [Patent Document 2] JP 2018-26961 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the switching power supply device described in Patent Document 2, the number of phases to be controlled is the same as the number of transistors, so the amount of control calculations is large.

[0006] An object of the present invention is to provide a power supply device capable of suppressing the amount of control calculation. [Means for solving the problem]

[0007] A power supply device according to one aspect of the present invention comprises: a first bridge circuit having a first terminal and a second terminal to which a first DC voltage is input; a second bridge circuit having a first terminal and a second terminal to which the first DC voltage is input; a first transformer having a primary winding electrically connected to a third terminal and a fourth terminal of the first bridge circuit; a second transformer having a primary winding electrically connected to the third terminal and the fourth terminal of the second bridge circuit and one end of a secondary winding electrically connected to one end of a secondary winding of the first transformer; a coil having one end electrically connected to the other end of the secondary winding of the first transformer; a third bridge circuit having a first terminal electrically connected to the other end of the coil and a second terminal electrically connected to the other end of the secondary winding of the second transformer, and outputting a second DC voltage from a third terminal and a fourth terminal; a control device that controls phases of the first bridge circuit, the second bridge circuit, and the third bridge circuit based on the first DC voltage and the second DC voltage, based on a primary side current and a secondary side current of the first transformer and the second transformer, or based on the first DC voltage, the second DC voltage, the primary side current and the secondary side current of the first transformer and the second transformer, and based on an output current command or an output power command; Equipped with It is characterized by:

[0008] In the power supply device, The control device includes: controlling phases of the first bridge circuit, the second bridge circuit, and the third bridge circuit based on a ratio value of the second DC voltage to the first DC voltage; It is characterized by:

[0009] In the power supply device, The control device includes: the phase difference between the first bridge circuit and the second bridge circuit is increased from 0 degrees as the value of the ratio decreases from 1; It is characterized by:

[0010] In the power supply device, The control device includes: determining a first phase difference between the first bridge circuit and a reference phase and between the reference phase and the second bridge circuit based on the value of the ratio, and aligning the phase of the third bridge circuit with the reference phase; It is characterized by:

[0011] In the power supply device, The control device includes: determining a second phase difference between the first bridge circuit and the second bridge circuit based on the value of the ratio, and determining a third phase difference between the first bridge circuit and the third bridge circuit and between the third bridge circuit and the second bridge circuit to be half of the second phase difference; It is characterized by: Effect of the Invention

[0012] Advantageous Effects of Invention The power supply device according to one aspect of the present invention provides an advantage in that it is possible to reduce the amount of control calculation. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing the configuration of a power supply device of a comparative example. [Diagram 2] FIG. 2 is a diagram illustrating a configuration of the power supply device according to the embodiment. [Diagram 3] FIG. 3 is a diagram illustrating an example of a phase difference between a reference phase and a bridge circuit according to the embodiment. [Figure 4] FIG. 4 is a diagram showing simulation waveforms of the power supply devices according to the embodiment and the comparative example. [Diagram 5] FIG. 5 is a diagram showing simulation waveforms of the power supply devices according to the embodiment and the comparative example. [Figure 6]FIG. 6 is a diagram showing a normalized transformer current of the power supply device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A power supply device according to an embodiment of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the embodiment.

[0015] <Embodiment Mode> An embodiment will be described below, but in order to facilitate understanding of the embodiment, a comparative example will be described first. (Comparative Example) 1 is a diagram showing the configuration of a power supply device of a comparative example. The power supply device 101 is a dual active bridge (DAB) that receives a DC voltage Vin that is output from a power supply 2 and smoothed by a capacitor 3, and outputs a DC voltage Vout to a load 4.

[0016] The power supply device 101 includes bridge circuits 11 and 13, a transformer 21, a coil 22, a capacitor 23, and a control device 102.

[0017] The bridge circuit 11 is a single-phase full-bridge circuit including transistors Tr1 to Tr4.

[0018] In the present disclosure, each transistor is a MOSFET, but is not limited to this. Each transistor may be a silicon power device, a GaN power device, a SiC power device, an IGBT (Insulated Gate Bipolar Transistor), or the like.

[0019] Each transistor has a parasitic diode (body diode). A parasitic diode is a pn junction between the back gate and the source and drain of a MOSFET. The parasitic diode can be used as a freewheeling diode to release the transient back electromotive force when the transistor is turned off.

[0020] The source of the transistor Tr1 is electrically connected to the drain of the transistor Tr2. The drain of the transistor Tr1 is electrically connected to the drain of the transistor Tr3. The source of the transistor Tr3 is electrically connected to the drain of the transistor Tr4. The source of the transistor Tr2 is electrically connected to the source of the transistor Tr4.

[0021] The connection point between the drain of the transistor Tr1 and the drain of the transistor Tr3 is one input terminal 11a of the bridge circuit 11. The connection point between the source of the transistor Tr2 and the source of the transistor Tr4 is the other input terminal 11b of the bridge circuit 11.

[0022] The connection point between the source of the transistor Tr1 and the drain of the transistor Tr2 is one output terminal 11c of the bridge circuit 11. The connection point between the source of the transistor Tr3 and the drain of the transistor Tr4 is the other output terminal 11d of the bridge circuit 11.

[0023] The input terminal 11a is electrically connected to one end (high potential end) of the capacitor 3. The input terminal 11b is electrically connected to the other end (low potential end) of the capacitor 3.

[0024] A DC voltage Vin is input between the input terminal 11a and the input terminal 11b.

[0025] The transformer 21 includes a primary winding 21a, a secondary winding 21b, and a core 21c. The primary winding 21a and the secondary winding 21b are wound around the core 21c.

[0026] The turns ratio between the primary winding 21a and the secondary winding 21b is 1:1, for example, but the present disclosure is not limited to this.

[0027] One end of the primary winding 21a is electrically connected to the output terminal 11c, and the other end of the primary winding 21a is electrically connected to the output terminal 11d.

[0028] The bridge circuit 11 outputs a DC voltage Vin or a DC voltage −Vin between an output terminal 11c and an output terminal 11d.

[0029] For example, when the transistors Tr1 and Tr4 are controlled to be in an on state and the transistors Tr2 and Tr3 are controlled to be in an off state, the bridge circuit 11 outputs a DC voltage Vin between the output terminals 11c and 11d.

[0030] Furthermore, for example, when the transistors Tr1 and Tr4 are controlled to be in an off state and the transistors Tr2 and Tr3 are controlled to be in an on state, the bridge circuit 11 outputs a DC voltage −Vin between the output terminals 11c and 11d.

[0031] One end of the coil 22 is electrically connected to one end of the secondary winding 21b.

[0032] The bridge circuit 13 is a single-phase full-bridge circuit including transistors Tr5 to Tr8.

[0033] The source of the transistor Tr5 is electrically connected to the drain of the transistor Tr6. The drain of the transistor Tr5 is electrically connected to the drain of the transistor Tr7. The source of the transistor Tr7 is electrically connected to the drain of the transistor Tr8. The source of the transistor Tr6 is electrically connected to the source of the transistor Tr8.

[0034] The connection point between the source of the transistor Tr5 and the drain of the transistor Tr6 is one input terminal 13a of the bridge circuit 13. The connection point between the source of the transistor Tr7 and the drain of the transistor Tr8 is the other input terminal 13b of the bridge circuit 13.

[0035] The connection point between the drain of the transistor Tr5 and the drain of the transistor Tr7 is one output terminal 13c of the bridge circuit 13. The connection point between the source of the transistor Tr6 and the source of the transistor Tr8 is the other output terminal 13d of the bridge circuit 13.

[0036] The input terminal 13a is electrically connected to the other end of the coil 22. The input terminal 13b is electrically connected to the other end of the secondary winding 21b.

[0037] The output terminal 13c is electrically connected to one end (high potential end) of the capacitor 23. The output terminal 13d is electrically connected to the other end (low potential end) of the capacitor 23.

[0038] The voltage of the capacitor 23 is the DC voltage Vout. One end (high potential end) of the capacitor 23 is electrically connected to one end (high potential end) of the load 4. The other end (low potential end) of the capacitor 23 is electrically connected to the other end (low potential end) of the load 4.

[0039] The control device 102 controls the bridge circuits 11 and 13. For example, the control device 102 controls the switching frequencies of the transistors Tr1 to Tr8 to be the same and the duty ratio to be 0.5. In addition, in the DAB, the phase difference between the input side and the output side is the command value of the output current. Therefore, the control device 102 controls the phase difference φ between the bridge circuits 11 and 13. 101 By controlling this, the output current (power) is controlled.

[0040] (Embodiment) Among the components of the power supply device of the embodiment, the same components as those in the comparative example are given the same reference numerals and description thereof will be omitted.

[0041] 2 is a diagram showing the configuration of a power supply device according to an embodiment. A power supply device 1 receives a DC voltage Vin that is output from a power supply 2 and smoothed by a capacitor 3, and outputs a DC voltage Vout to a load 4.

[0042] Compared to power supply device 101 (see FIG. 1), power supply device 1 includes transformers 21-1 and 21-2 instead of transformer 21. Compared to power supply device 101, power supply device 1 further includes a bridge circuit 12. Compared to power supply device 101, power supply device 1 includes a control device 31 instead of control device 102. Compared to power supply device 101, power supply device 1 further includes voltage sensors 24 and 25.

[0043] The bridge circuit 11 corresponds to an example of a "first bridge circuit" in the present disclosure. The bridge circuit 12 corresponds to an example of a "second bridge circuit" in the present disclosure. The bridge circuit 13 corresponds to an example of a "third bridge circuit" in the present disclosure.

[0044] The transformer 21-1 corresponds to an example of a "first transformer" in the present disclosure, and the transformer 21-2 corresponds to an example of a "second transformer" in the present disclosure.

[0045] The transformer 21-1 includes a primary winding 21-1a, a secondary winding 21-1b, and a core 21-1c. The primary winding 21-1a and the secondary winding 21-1b are wound around the core 21-1c.

[0046] The turns ratio between the primary winding 21-1a and the secondary winding 21-1b is exemplified as 2:1, but the present disclosure is not limited to this.

[0047] One end of the primary winding 21-1a is electrically connected to one output terminal 11c of the bridge circuit 11. The other end of the primary winding 21-1a is electrically connected to the other output terminal 11d of the bridge circuit 11.

[0048] The circuit configuration of the bridge circuit 12 is similar to that of the bridge circuit 11, and therefore a description thereof will be omitted.

[0049] One input terminal 12a of the bridge circuit 12 is electrically connected to one end (high potential end) of the capacitor 3. The other input terminal 12b of the bridge circuit 12 is electrically connected to the other end (low potential end) of the capacitor 3.

[0050] In other words, the input sides of the bridge circuit 11 and the bridge circuit 12 are connected in parallel.

[0051] The transformer 21-2 includes a primary winding 21-2a, a secondary winding 21-2b, and a core 21-2c. The primary winding 21-2a and the secondary winding 21-2b are wound around the core 21-2c.

[0052] The turns ratio between the primary winding 21-2a and the secondary winding 21-2b is exemplified as 2:1, but the present disclosure is not limited to this.

[0053] One end of the primary winding 21-2a is electrically connected to one output terminal 12c of the bridge circuit 12. The other end of the primary winding 21-2a is electrically connected to the other output terminal 12d of the bridge circuit 12.

[0054] One end of the coil 22 is electrically connected to one end of the secondary winding 21-1b. The other end of the secondary winding 21-1b is electrically connected to one end of the secondary winding 21-2b.

[0055] That is, the secondary winding 21-1b and the secondary winding 21-2b are connected in series.

[0056] The other end of the secondary winding 21-2b is electrically connected to the other input terminal 13b of the bridge circuit 13.

[0057] The voltage sensor 24 detects the input voltage of the power supply device 1 , that is, the DC voltage Vin, and outputs it to the control device 31 .

[0058] The voltage sensor 25 detects the output voltage of the power supply device 1 , that is, the DC voltage Vout, and outputs it to the control device 31 .

[0059] The control device 31 includes a first switching control section 31a, a second switching control section 31b, a third switching control section 31c, and a phase control section 31d.

[0060] For example, the first switching control unit 31a, the second switching control unit 31b, and the third switching control unit 31c control the switching frequencies of the transistors in the bridge circuits 11, 12, and 13 to be the same and the duty ratio to be 0.5.

[0061] The phase control unit 31d determines a phase difference φ between the bridge circuit 11 and the bridge circuit 12 based on the ratio of the DC voltage Vout to the DC voltage Vin and an output current (or output power) command. 1-2 , and a phase difference φ between the bridge circuits 11 and 12 and the bridge circuit 13. The first switching control unit 31a and the second switching control unit 31b determine the phase difference φ 1-2 Based on the phase difference φ, the third switching control unit 31c outputs a switching control signal to the bridge circuit 13. In this way, the control device 31 controls the output current (power).

[0062] The first, second and third switching control sections 31a, 31b and 31c only need to control the phase in units of bridge circuits (three circuits), and do not need to control the phase in units of transistors (12 circuits).

[0063] In the embodiment, as an example, the phase control unit 31d controls a reference phase φ REF and set the reference phase φ REF The phase difference of the bridge circuits 11, 12 and 13 with respect to

[0064] FIG. 3 is a diagram illustrating an example of a phase difference between a reference phase and a bridge circuit according to the embodiment.

[0065] As shown by point 201, when the ratio of the DC voltage Vin to the DC voltage Vout is 1:1, that is, when the ratio of the DC voltage Vin to the DC voltage Vout is 1, the phase control unit 31d outputs a reference phase φ REFand the bridge circuits 11 and 12 to ±0 degrees. In other words, the phase control unit 31d determines the phase difference φ 1-2 is determined to be 0 degrees.

[0066] Reference phase φ REF and the bridge circuits 11 and 12 corresponds to an example of a “first phase difference” in the present disclosure.

[0067] In the embodiment, for ease of understanding, the reference phase φ REF However, the present disclosure is not limited to this. For example, the phase control unit 31d may determine a second phase difference between the bridge circuit 11 and the bridge circuit 12 based on the value of the ratio of the DC voltage Vout to the DC voltage Vin. Then, the phase control unit 31d may determine a third phase difference between the bridge circuit 11 and the bridge circuit 13 and between the bridge circuit 13 and the bridge circuit 12 (for example, to half the second phase difference).

[0068] Fig. 4 is a diagram showing simulation waveforms of the power supply devices of the embodiment and the comparative example. Fig. 4 shows a case where the voltage ratio is 1:0.5. The output power is 0 W, and the phase difference φ, which is the output command value, is 0 degrees.

[0069] As described above, in the embodiment, when the ratio of the DC voltage Vin to the DC voltage Vout is 1:0.5, the phase difference φ 1-2 is 120 degrees.

[0070] FIG. 4(a) shows the transformer voltage Vt of the secondary windings 21-1b and 21-2b of the embodiment and the transformer voltage Vt of the secondary winding 21b of the comparative example. 101 Shows.

[0071] FIG. 4B shows the coil voltage VL of the coil 22 of the embodiment and the coil voltage VL of the coil 22 of the comparative example. 101 Shows.

[0072] FIG. 4(c) shows the transformer current It of the secondary windings 21-1b and 21-2b of the embodiment and the transformer current It of the secondary winding 21b of the comparative example. 101 Shows.

[0073] FIG. 4(d) shows the secondary current I2 of the embodiment and the secondary current I2 of the comparative example. 101 Shows.

[0074] As shown in FIG. 4(a), the transformer voltage Vt is a positive voltage during a period T0 when the bridge circuit 11 is in a positive phase and the bridge circuit 12 is in a positive phase. The transformer voltage Vt is a negative voltage during a period T1 when the bridge circuit 11 is in a negative phase and the bridge circuit 12 is in a negative phase negative. The transformer voltage Vt is 0 V during other periods. The control device 31 controls the phase difference φ 1-2 In other words, the controller 31 controls the length of the positive period T0 and the negative period T1 of the transformer voltage Vt by controlling the phase difference φ 1-2 By controlling the effective value of the transformer voltage Vt, the effective value of the transformer voltage Vt can be controlled.

[0075] 4(b), the coil voltage VL is a voltage obtained by offsetting the transformer voltage Vt in the negative direction by the DC voltage Vout during a period T2 when the bridge circuit 13 is in the positive phase. Also, the coil voltage VL is a voltage obtained by offsetting the transformer voltage Vt in the positive direction by the DC voltage Vout during a period T3 when the bridge circuit 13 is in the negative phase. The control device 31 can control the coil voltage VL by controlling the phase difference φ.

[0076] As shown in FIG. 4(c), the transformer current It increases linearly during a period T4 in which the coil voltage VL is a positive voltage, and decreases linearly during a period T5 in which the coil voltage VL is a negative voltage.

[0077] As shown in FIG. 4(d), the current I2 101 becomes smaller compared to

[0078] Fig. 5 is a diagram showing simulation waveforms of the power supply devices of the embodiment and the comparative example. Fig. 5 shows a case where the voltage ratio is 1:0. The output power is 0 W, and the phase difference φ, which is the output command value, is 0 degrees.

[0079] As described above, in the embodiment, when the ratio of the DC voltage Vin to the DC voltage Vout is 1:0, the phase difference φ 1-2 is 180 degrees.

[0080] FIG. 5(a) shows the transformer voltage Vt of the secondary windings 21-1b and 21-2b of the embodiment and the transformer voltage Vt of the secondary winding 21b of the comparative example. 101 Shows.

[0081] FIG. 5B shows the coil voltage VL of the coil 22 of the embodiment and the coil voltage VL of the coil 22 of the comparative example. 101 Shows.

[0082] FIG. 5(c) shows the transformer current It of the secondary windings 21-1b and 21-2b of the embodiment and the transformer current It of the secondary winding 21b of the comparative example. 101 Shows.

[0083] FIG. 5(d) shows the secondary current I2 of the embodiment and the secondary current I2 of the comparative example. 101 Shows.

[0084] As shown in FIG. 5(a), the transformer voltage Vt is 0 V over the entire period because the phase of the bridge circuit 11 and the phase of the bridge circuit 12 are shifted by 180 degrees.

[0085] As shown in FIG. 5(b), the coil voltage VL is 0 V over the entire period because the transformer voltage Vt is 0 V over the entire period and the DC voltage Vout is 0 V.

[0086] As shown in FIG. 5(c), the transformer current It is 0 A over the entire period because the coil voltage VL is 0 V over the entire period.

[0087] As shown in FIG. 5(d), the current I2 is 0 A over the entire period.

[0088] Fig. 6 is a diagram showing a normalized transformer current of the power supply device according to the embodiment. Fig. 6 shows a range in which the ratio of the DC voltage Vin to the DC voltage Vout is from 1:1 (the ratio value is 1) to 1:0 (the ratio value is 0).

[0089] Waveform 211 shows the normalized transformer current It of the power supply device 1 of the embodiment. Waveform 212 shows the normalized transformer current It of the power supply device 101 of the comparative example. 101 Reference numeral 221 indicates the case where the ratio between the DC voltage Vin and the DC voltage Vout is 1:0.5 (the ratio value is 0.5) (see the simulation waveform in FIG. 4). Reference numeral 222 indicates the case where the ratio between the DC voltage Vin and the DC voltage Vout is 1:0 (the ratio value is 0) (see the simulation waveform in FIG. 5).

[0090] As shown in FIG. 6, the power supply device 1 converts the transformer current It into a transformer current It 101 In particular, the power supply device 1 can suppress the transformer current It when the ratio of the DC voltage Vin to the DC voltage Vout is 1:0, that is, when the secondary side is drooping (short circuited), by reducing the transformer current It 101 can be suppressed to a greater extent than

[0091] Moreover, the power supply device 1 only needs to control the phases in units of bridge circuits (three units). Therefore, the power supply device 1 can reduce the number of phases to be controlled compared to Patent Document 2 (controlling the phase in units of transistors), and therefore the amount of control calculations can be reduced.

[0092] Furthermore, on the primary side of the power supply device 1, the primary current is split into two bridge circuits 11 and 12, so that inexpensive components can be used for the bridge circuits 11 and 12 on the primary side, thereby making it possible to suppress component costs.

[0093] In the embodiment, the bridge circuits 11, 12, and 13 are single-phase full-bridge circuits, but the present disclosure is not limited to this. The bridge circuits 11, 12, and 13 may be three-phase bridge circuits.

[0094] In the embodiment, the control device 31 controls the phases of the bridge circuits 11, 12, and 13 based on the ratio of the DC voltage Vout to the DC voltage Vin, but the present disclosure is not limited to this. The control device 31 may control the phases of the bridge circuits 11, 12, and 13 based on the primary and secondary currents of the transformers 21-1 and 21-2. The control device 31 may control the phases of the bridge circuits 11, 12, and 13 based on the DC voltage Vin, the DC voltage Vout, and the primary and secondary currents of the transformers 21-1 and 21-2.

[0095] <Additional Notes> A DC blocking capacitor may be provided in each bridge circuit. For example, DC blocking capacitors may be provided in the output terminals 11c and 11d of the bridge circuit 11, the output terminals 12c and 12d of the bridge circuit 12, and the input terminals 13a and 13b of the bridge circuit.

[0096] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0097] 1, 101 power supply 2 power supply 3, 23 Capacitor 4. Load 11, 12, 13 Bridge circuit 21, 21-1, 21-2 Trans 22 Coil 24, 25 Voltage sensor 31, 102 Control device 31a First switching control section 31b Second switching control section 31c Third switching control section 31d Phase control section

Claims

1. a first bridge circuit having a first terminal and a second terminal to which a first DC voltage is input; a second bridge circuit having a first terminal and a second terminal to which the first DC voltage is input; a first transformer having a primary winding electrically connected to a third terminal and a fourth terminal of the first bridge circuit; a second transformer having a primary winding electrically connected to the third terminal and the fourth terminal of the second bridge circuit and one end of a secondary winding electrically connected to one end of a secondary winding of the first transformer; a coil having one end electrically connected to the other end of the secondary winding of the first transformer; a third bridge circuit having a first terminal electrically connected to the other end of the coil and a second terminal electrically connected to the other end of the secondary winding of the second transformer, and outputting a second DC voltage from a third terminal and a fourth terminal; a control device that performs control such that a phase difference between the first bridge circuit and the second bridge circuit is increased from 0 degrees as a ratio value of the second DC voltage to the first DC voltage decreases from 1 when the second DC voltage is lower than the first DC voltage; Equipped with A power supply device comprising:

2. The control device includes: determining a first phase difference between the first bridge circuit and a reference phase and between the reference phase and the second bridge circuit based on the value of the ratio, and aligning the phase of the third bridge circuit with the reference phase; 2. The power supply device according to claim 1 .

3. The control device includes: determining a second phase difference between the first bridge circuit and the second bridge circuit based on the value of the ratio, and determining a third phase difference between the first bridge circuit and the third bridge circuit and between the third bridge circuit and the second bridge circuit to be half of the second phase difference; 2. The power supply device according to claim 1 .

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